In most cases, diode devices, whose conducting-state resistance changes with the value of an applied analog control voltage, are used as attenuators for HF signals. The function of the damping change differs and is closely linked with the amplitude applied, the temperature, the circuit design, and ultimately with the type of the diodes. Calibration in decibels can be achieved by inserting an amplifier with a logarithmic characteristic. An analog control signal for the attenuator is generated in a control signal generator from an input signal that represents the desired damping.
The setting of the control signal generator according to the existing damping characteristics and the temperature dependences of components of the control signal generator, which adjustment must be performed individually for every single damping device, has proved to be especially problematic. This problem is particularly, acute when the damping is to be set according to input signals present in different forms (analog/digital).